Copolymerization of carbon monoxide and olefin with diphosphine having heterocyclic substituents as catalyst

Abstract

Diphosphines having at least one heterocyclic substituent that includes at least one oxygen, sulphur, or nitrogen atom in a five or six membered ring are useful components in palladium catalyst compositions which have been used to polymerize carbon monoxide and olefinically unsaturated compounds. Remaining substituents, if any, are carbocyclic hydrocarbon groups such as phenyls which are preferably substituted with polar groups in a ring position ortho to the phosphorus. The phosphorus atoms in the diphosphine are connected by a bridging group that contains at least one carbon atom.

What is claimed is: 
     
       1. An improved process for preparing polymers, wherein carbon monoxide is polymerized with olefinically unsaturated compounds in the presence of a palladium catalyst composition comprising a palladium compound, anions of an acid having a pKa less that about 6, and a diphosphine ligand, the improvement wherein the diphosphine ligand is of the general formula ##STR10## wherein each R 2  is independently a similar or different carbocyclic hydrocarbon group, or a similar or different heterocyclic substituent selected from 2-pyridyl, 2-furyl or 2-thienyl groups, which substituent is bound to the phosphorus atom by one of the carbon atoms in the ring of the substituent, at least one R 2  being the heterocyclic substituent, and wherein R represents a bivalent bridging group containing at least one carbon atom in the bridge. 
     
     
       2. The process of claim 1, wherein the olefinically unsaturated compound is predominantly ethene and the polymerization temperature is 30-150° C., the polymerization pressure is 20-100 bar, the molar ratio of the olefinically unsaturated compounds relative to carbon monoxide is 5:1-1:2, and the catalyst composition contains 10 -6  -10 -4  gram atom of palladium per mol olefinically unsaturated compound. 
     
     
       3. The process of claim 2, wherein a small amount of propylene is polymerized with the ethene and the carbon monoxide. 
     
     
       4. The process of claim 1, wherein the palladium compound is a palladium salt of a carboxylic acid. 
     
     
       5. The process of claim 1, wherein the acid in the catalyst composition has a pKa less than 2. 
     
     
       6. The process of claim 1, wherein the heterocyclic substituent in the diphosphine ligand is 2-pyridyl or 2-furyl groups. 
     
     
       7. The process of claim 6, wherein each R 2  is the heterocyclic substituent. 
     
     
       8. The process of claim 1, wherein one heterocyclic substituent and one carbocyclic hydrocarbon group are joined to each phosphorus atom the diphosphine ligand. 
     
     
       9. The process of claim 8, wherein each carbocyclic hydrocarbon group in the diphosphine ligand is substituent with polar groups. 
     
     
       10. The process of claim 9, wherein the polar groups are phenyl groups, 2-methoxyphenyl groups, or 2,4-dimethoxyphenyl groups.